CVE-2021-41194
9.1 · CRITICALOverview
CVE-2021-41194 is a critical-severity vulnerability affecting jupyterhub first_use_authenticator. It was published on October 28, 2021 and has a CVSS 3.1 base score of 9.1 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
FirstUseAuthenticator is a JupyterHub authenticator that helps new users set their password on their first login to JupyterHub. When JupyterHub is used with FirstUseAuthenticator, a vulnerability in versions prior to 1.0.0 allows unauthorized access to any user's account if `create_users=True` and the username is known or guessed. One may upgrade to version 1.0.0 or apply a patch manually to mitigate the vulnerability. For those who cannot upgrade, there is no complete workaround, but a partial mitigation exists. One can disable user creation with `c.FirstUseAuthenticator.create_users = False`, which will only allow login with fully normalized usernames for already existing users prior to jupyterhub-firstuserauthenticator 1.0.0. If any users have never logged in with their normalized username (i.e. lowercase), they will still be vulnerable until a patch or upgrade occurs.
Remediation
Check the references section for vendor advisories and patches from jupyterhub. Update first_use_authenticator to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| jupyterhub | first_use_authenticator | >= 0, < 1.0.0 | Affected |
References
Frequently Asked Questions
What is CVE-2021-41194?
CVE-2021-41194 is a critical-severity vulnerability affecting jupyterhub first_use_authenticator. It was published on October 28, 2021 and has a CVSS 3.1 base score of 9.1 (CRITICAL).
How severe is CVE-2021-41194?
This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-41194?
Check the references section for vendor advisories and patches from jupyterhub. Update first_use_authenticator to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-41194?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-41194 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
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Browser-based exploitation validates findings with real proof-of-concept.
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